Body-on-frame, also known as ladder frame construction, is a common

motor vehicle A motor vehicle, also known as motorized vehicle or automotive vehicle, is a self-propelled land vehicle, commonly wheeled, that does not operate on rails (such as trains or trams) and is used for the transportation of people or cargo. The ...

construction method, whereby a separate body or coach is mounted on a strong and relatively rigid

vehicle frame A vehicle frame, also historically known as its ''chassis'', is the main supporting structure of a motor vehicle to which all other components are attached, comparable to the skeleton of an organism. Until the 1930s, virtually every car had ...

chassis A chassis (, ; plural ''chassis'' from French châssis ) is the load-bearing framework of an artificial object, which structurally supports the object in its construction and function. An example of a chassis is a vehicle frame, the underpa ...

that carries the powertrain (the engine and

drivetrain A drivetrain (also frequently spelled as drive train or sometimes drive-train) is the group of components that deliver mechanical power from the prime mover to the driven components. In automotive engineering, the drivetrain is the components ...

) and to which the wheels and their suspension, brakes, and steering are mounted. While this was the original method of building automobiles, body-on-frame construction is now used mainly for heavy

truck A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame constructi ...

s, pickups, and predominantly large

SUVs A sport utility vehicle (SUV) is a car classification that combines elements of road-going passenger cars with features from off-road vehicles, such as raised ground clearance and four-wheel drive. There is no commonly agreed-upon definit ...

. In the late 19th century the frames, like those of the carriages they replaced, might be made of wood (commonly

ash Ash or ashes are the solid remnants of fires. Specifically, ''ash'' refers to all non-aqueous, non- gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash ...

), reinforced by steel flitch plates – but in the early 20th century steel ladder frames or chassis rapidly became standard. Mass production of all-metal bodies began with the Budd Company and the Dodge Brothers. Mass production of all-metal bodies became general in the 1920s but Europe, with exceptions, followed almost a decade later. Europe's custom-made or "coachbuilt" cars usually contained some wood framing or used aluminium alloy castings. Towards the beginning of international automobile assembly and construction, most manufacturers created rolling chassis consisting of a powertrain, suspension, steering column and a fuel tank that was then sent to a

coachbuilder A coachbuilder or body-maker is someone who manufactures bodies for passenger-carrying vehicles.Construction has always been a skilled trade requiring a relatively lightweight product with sufficient strength. The manufacture of necessarily ...

that added the body, interior and upholstery to the customers specific requests. In contrast,

unibody A vehicle frame, also historically known as its ''chassis'', is the main supporting structure of a motor vehicle to which all other components are attached, comparable to the skeleton of an organism. Until the 1930s, virtually every car had ...

monocoque Monocoque ( ), also called structural skin, is a structural system in which loads are supported by an object's external skin, in a manner similar to an egg shell. The word ''monocoque'' is a French term for "single shell". First used for boats, ...

designs, where panels within the body supported the car on its suspension, were developed by European manufacturers in the late 1920s with Budd USA (which had a number of large factories in Europe) and its technical knowhow. Because of the high cost of designing and developing these structures and the high cost of specialised machinery to make the large pressings required by this style of construction it is not used by low-volume manufacturers, who might construct an equivalent by welding steel tube to form a suitable space frame.

History

Ford model t 1919 d044 lubrication chart

The

Ford Model T The Ford Model T is an automobile that was produced by Ford Motor Company from October 1, 1908, to May 26, 1927. It is generally regarded as the first affordable automobile, which made car travel available to middle-class Americans. The relat ...

carried the tradition of body-on-frame over from horse-drawn buggies, helping to facilitate high volume manufacturing on a moving assembly line. In the United States, frequent changes in

automotive design Automotive design is the process of developing the appearance (and to some extent the ergonomics) of motor vehicles - including automobiles, motorcycles, trucks, buses, coaches, and vans. The functional design and development of a modern ...

made it necessary to use a ladder frame rather than unibody construction to make it possible to change the design without having to change the

, allowing frequent changes and improvements to the car's bodywork and interior (where they were most noticeable to customers) while leaving the chassis and driveline unchanged, and thus keeping costs down and design times short. It was also easy to use the same chassis and driveline for several very different cars. Especially in the days before computer-aided design, this was an advantage. Most small passenger vehicles switched to

construction by the end of the 1930s. The trend had started with cars like the Citroën Traction Avant (1934) and Opel Olympia (a General Motors design) introduced in 1935, and the

Chrysler Airflow The Chrysler Airflow is a full-size car produced by Chrysler from 1934 to 1937. The Airflow was the first full-size American production car to use streamlining as a basis for building a sleeker automobile, one less susceptible to air resistance. ...

Truck A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame constructi ...

bus manufacturers A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for ...

and large low volume cars or those made in the United States continued to use separate bodies on "conventional" frames. Body-on-frame remains the preferred construction method for heavy-duty commercial vehicles (especially those intended to carry or pull heavy loads, such as trucks and some

sport utility vehicles A sport utility vehicle (SUV) is a car classification that combines elements of road-going passenger cars with features from off-road vehicles, such as raised ground clearance and four-wheel drive. There is no commonly agreed-upon definition ...

(SUVs)) but as production volumes rise increasing numbers of SUVs and crossover SUVs are switching to

frames. Mass-market manufacturers Ford, General Motors and

Chrysler Stellantis North America (officially FCA US and formerly Chrysler ()) is one of the " Big Three" automobile manufacturers in the United States, headquartered in Auburn Hills, Michigan. It is the American subsidiary of the multinational automot ...

are abandoning true body-on-frame SUVs, opting, when sales volume permits, for more efficient unibody construction.

Toyota is a Japanese multinational automotive manufacturer headquartered in Toyota City, Aichi, Japan. It was founded by Kiichiro Toyoda and incorporated on . Toyota is one of the largest automobile manufacturers in the world, producing about 10 ...

currently manufactures the most body-on-frame SUVs with the 4Runner, Sequoia, Land Cruiser, Lexus GX and LX followed by Nissan with the

Patrol A patrol is commonly a group of personnel, such as law enforcement officers, military personnel, or security personnel, that are assigned to monitor or secure a specific geographic area. Etymology From French ''patrouiller'', from Old Frenc ...

Armada Armada is the Spanish and Portuguese word for naval fleet, which also adopted into English, Malay and Indonesian for the same meaning, or an adjective meaning 'armed'; Armáda () is the Czech and Slovak word for armed forces. Armada may also refe ...

, and Infiniti QX56/80.

Examples

The following is a list of production cars, SUVs, and light-duty pickup trucks that currently have a body-on-frame construction. The list is divided by vehicle category.

References

External links

Ford assembly line featuring body-on-frame car (historic)
{{DEFAULTSORT:Body-On-Frame Automotive chassis types Structural system Structural engineering

History

Examples

See also

References

External links